The goals of this project are as follows. (1) to increase our understanding of the emotional reactivity of developing animals to unfamiliar, fear-arousing environments and to painful stimulation. Is the young animal for example, hyper-reactive to those stimuli? (2) If the young of a species are hyper-reactive to emotion-arousing conditions, are there naturally-occurring stimuli in the environment that calm or reduce those states? If so, how effective are they and how quickly do they act as "calming" or "safety" stimuli? (3) To understand the effects of heightened emotional reactivity on sensory information processing (as measured by the orienting response) and on learning and memory. During the period of hyper-arousal is the young animal more or less likely to perceive and encode new incoming information? (4) To determine whether the young aninal is more likely than an adult to show cross-modal transfer of acquired information? Similarly, is overshadowing and facilitation more likely to occur in infants than adults? (5) To increase our understanding of the role of autonomic activity in the ontogeny of long-term memory. For example, which shows the greatest loss over time: the autonomic or somato-motor components of conditioned fear? After a long retention interval, which is elicited first by the conditioned stimulus: the autonomic or somato-motor responses? Does one trigger the reappearance of the other? (6) To understand the interrelationships between the somato-motor and autonomic responses in the reinstatement process. Are both the autonomic and somato-motor components of memory reactivated simultaneously? Or does one occur before the other? If so, does reactivation of the emotional component stimulate reactivation on the somato-motor behavior?